Calculating instrument.



E. HILL.

CALCULATING INSTRUMENT. APPLICATION FILED APR. 12, 19 15- 1,145,020. Patented July 6,1915.

UNITED STATES PATENT OFFICE.

EBENEZER HILIQOF SOUTH NOR-WALK, CONNECTICUT. A

CALCULATING INSTRUMENT.

I To all whom it may concern Be it known that I, EBENEZER HILL, a citizen of the United States, residing at South N orwalk, in the county of Fairfield and State. of Connecticut, have invented a new .and useful Improvement in Calculating Instruments, of which the following is a speci fication.

This invention relates to an instrument which is designed for mechanically obtaining one of the factors employed in calculating the exact position of a body or locality on the earth, such for instance as the po- I sition of a ship at sea. One of the necessary steps in'solvin'g such problems 1n navigation is to obtain the hour angle, that is, the distance in hours, minutes and seconds away from the merldlan at a given time and at a given longitude of a selected star or as cardboard or celluloid, having difierent diameters and rotarily mounted with relation to I each other, with a wire or line which represents meridian extending radially across or visible from the front of the disks from the common axis of the disks to the peripheryv of the largest or bottom disk. The top or smallest disk 1 is termed the longitude disk, and it is divided about its perimeter in each direction from zero marked G which stands for Greenwich, into 180 degrees and fractions thereof, one side representing west longitude and the other side east longitude, and the disk being so lettered. The second disk 2, which is somewhat larger than the first is termed the sun disk, or the Greenwich mean tlme disk. Around the exposed portion of the perimeter this disk from zero, represented by the arbitrary symbol of the sun, is divided by graduations into hours and minutes from 1 to 12 on the first half and then continuing from 1 to 12 on the second half,

Specification of Letters Patent.

Application filed April 12, 1915. Serial N 0. 20,596.

Patented July 6, 1915.

these graduations representing the morning and afternoon hours of a day. The hour graduations on the sun disk register with the degree graduations on the longitude disk. The third or middle disk 3 is termed the Aries disk or the right ascension disk. This disk is somewhat larger than the second disk and its exposed perimeter is graduated from zero, represented by the symbol of .Ariesthe sign of the zodiac-into hours and minutes from 1 to 24. The 1 to 24 hour graduations on the Aries disk register with the 1 to 12 hour graduations on the sun disk.

The fourth disk 4, which is larger than the third disk, is termed the star disk, and from zero represented by a star, the exposed perimeter of the disk is marked in 'hours and minutes from 1 to 24: in a reverse direction to that in which the hours are marked on the Aries disk. The fifth or bottom disk 5, which is the largest, is the time disk or the hour angle disk. This is marked about its exposed periphery from the meridian line or'zero in hours from 1 to 12 in each direction. The meridian line is desirably formed by the wire -6 which extends from the, common axis of the disks, which may be held together by a portion of the meridian wire, to the zero point of the largest or time disk, so that all of the disks except the bottom are capable of being rotated independently or together in both directions with relation to the meridian line and the time disk.

This device is used in connection with the dead reckoning position of a ship and with the known factors taken from the Nautical Almanac, and the various disks are moved with relation to each other and in combination with. each other to obtain the final redisks have been properly nometer being 12 h.50. In this problem the dead reckonin position is taken to be 4323N and 6 W. From the NauticaZAZmanac it is found that at this time the right ascension of this star is 1320 and the right ascension of mean sun is 8h.15'.

' sult, which is read on the bottom or time disk is 12- 50.

In solving this problem, being in west longitude, the longitude disk is turned West ward until the reading from G or Greenwich with relation to the hours on the sun is, the longitude disk and the sun disk are then together rotated until the sun sign on the latter comes to 8 111-15 on the Aries disk, this factor, 8 h.- '15, being the right ascension of the mean sun at the hour and date" as taken from the Nautical Almanac. These three disks, the longitude disk, the

, sun disk and the Aries disk are then tothe star disk, or as appears in the drawings is 3 h.8'-, which'isthe answer to the problem assumed. This. factor is then used by the usual method of calculation for obtainingjhe final result.

- he instrument may be used for showing the value t in navigating problems with- I out makingrthe usual long arithmetical calculation. he device is also serviceable for graphically illustrating to students the method of making these calculations.

.The invention claimed is;

" ,1. 'A'calculating instrument-comprising a I series of superposed, pivotally connected .disks of different diameters, one disk having itsperimeter provided with graduations representing 180 of each'and 180 degrees of p west longitude, onedisk having its perimeter provided withgraduations reading continuously representlng twelve hours of morning and twelve hours of afternoon, one disk having its perimeter provided with graduations reading contra-clockwise representing twenty-four hours of a day, one disk having its perimeter provided with 'graduations reading clockwise representing twenty fourhours of a' d y, and one disk having its perimeter prov'ded with graduations reading oppositely and representing twelve hourly periods in both directionsfrom a zero at the meridianal line, and a meridian line extending radially with relationto said disks and Both of these disks, that immovable with relation to the. last mehtioned disk.'

2. A calculating instrument comprising a disk graduated into 360 degrees of longitude and reading in opposite directions from 0 to 180, a disk graduated into twenty-four hours and reading continuously from 0 to 12 and 0 to 12, a disk graduated into hours and reading from 0 to 24 contra-clockwise, a"

disk graduated into hours and reading from twenty-four'hours and reading in opposite directions from 0 to 12,'and a meridianline series of superposed disksofdifierent diameters pivotally mounted on a wire that extends radially from the common axis over the disks to the largest disks, one disk being graduated in degrees and reading in opposite directions from 0 to 180, one disk belng graduated in hours and reading continuously from 0 to 12 and 0 to 12, one disk being graduated in hours and reading from 0 to 2&1 contra-clockwise, one disk being graduated in hours and reading from 0' to 24 elockwis' and one disk being graduated in hours an reading in opposite directions -from0to12.

A calculatin instrument comprising a disk graduated with the hours of mormng and afternoon reading. continuously, a disk graduated with the hours-ofthe day reading contra-clockwise, a disk graduatedwith the hours of the day reading clockwise, a disk graduated with the hourlyperiods in opposite directions froma'meridi anal line, anda meridian line fixed with relation to the last mentioned disk. 7

- 5. A calculating instrument comprising a series of su'perposedfiisks of different diameters, a wire pivotally connecting said disks at the'common axis thereof, said wire extending to and having its outer end fixed to the largest disk whereby all of the disks are rotatable with relation to the largest disk and the wire on which they are pivoted, said disks having their exposed perimeters .grad-' uated respectively with degrees of longitude,

graduated with degrees of longitude, a-

hours of morning and afternoon, and hours 65 0 to 24 clockwise, a disk graduated into 

